I'm not so surprised by the lack of clarity. Once the word is out there, the momentum for a rally is no longer entirely, or possibly even much at all, under the control of the original organizers.

ETA: At least one statement of non-cancellation from ... I'm not actually sure if these are the original organizers, but it's plausible from their twitter stream? Also retweet of an un-cancellation from one of the speakers the Globe article said had cancelled.

ETA2: "Boston ‘free speech’ rally going ahead despite defections."